The number of reported new positive cases (by date of specimen) has been increasing exponentially for the last two weeks, resulting from the rapid growth of the B.1.1.529 variant, known as omicron, particularly in GL. In contrast to the cases, admissions to hospitals have just started to rise after a period of decline, with, again, the increase particularly pronounced in GL. The prevalence of infection, as estimated by the ONS Coronavirus Infection Survey, is around 1.70% showing no real change from previous weeks. It is, as yet, too early for the omicron variant to have any impact on the numbers of deaths. As there is no clear signal from omicron in the data that we use (ONS prevalence, deaths, serological swabbing), it would appear that what is being estimated here is a summary for pandemic infection with the delta variant. This would, for example, explain a number of infections that is markedly lower than the daily reported number of SARS-CoV-2 cases.
Bearing this in mind, our estimates show a pandemic with Rt values estimated mainly very close to 1. This is reflected in infection incidence which has remained generally constant, apart from in GL and the EE where the number of infections has started to increase.
Plots of the IFR over time show that we are currently estimating a decreasing IFR in all age groups with the most steep fall in the younger age groups. Following this drop, the overall IFR is 0.24% (0.22%–0.25%), highest in the over-75s at 3.1% (2.9%–3.4%), similar to that estimated in our most recent publication.
Real-time tracking of an epidemic, as data accumulate over time, is an essential component of a public health response to a new outbreak. A team of statistical modellers at the MRC Biostatistics Unit (BSU), University of Cambridge, are working to provide regular now-casts and forecasts of COVID-19 infections and deaths. This information feeds directly to the SAGE sub-group, Scientific Pandemic Influenza sub-group on Modelling (SPI-M), and to regional Public Health England (PHE) teams.
We fit a transmission model (Birrell et al. 2020) to a number of data sources (see ‘Data Sources’), to reconstruct the number of new COVID-19 infections over time in different age groups and NHS regions, estimate a measure of ongoing transmission and predict the number of new COVID-19 deaths.
We use:
Data are stratified into eight age groups: <1, 1-4, 5-14, 15-24, 25-44, 45-64, 65-74, 75+, and the NHS England regions (North East and Yorkshire, North West, Midlands, East of England, London, South East, South West).
Value of \(R_t\), the average number of secondary infections due to a typical infection today.
The percentage of a given group that has been infected.
NB: negative growth rates are rates of decline. Values are daily changes.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 0.00 | -0.01 | 0.01 |
| East of England | 0.01 | 0.00 | 0.02 |
| East Midlands | -0.03 | -0.05 | -0.01 |
| London | 0.00 | -0.01 | 0.02 |
| North East | -0.03 | -0.05 | -0.01 |
| North West | 0.00 | -0.02 | 0.02 |
| South East | -0.01 | -0.02 | 0.01 |
| South West | 0.00 | -0.02 | 0.01 |
| West Midlands | 0.00 | -0.02 | 0.01 |
| Yorkshire and The Humber | -0.01 | -0.03 | 0.01 |
Halving times in days, if a region shows growth than value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 1011.36 | 109.89 | NA |
| East of England | NA | 185.04 | NA |
| East Midlands | 25.22 | 14.96 | 77.21 |
| London | NA | 71.74 | NA |
| North East | 24.52 | 14.23 | 91.25 |
| North West | 658.97 | 27.72 | NA |
| South East | 137.13 | 36.38 | NA |
| South West | 140.26 | 33.66 | NA |
| West Midlands | 235.81 | 34.11 | NA |
| Yorkshire and The Humber | 57.51 | 20.07 | NA |
Doubling times in days, if a region shows decline then the value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | NA | 117.84 | NA |
| East of England | 80.55 | 35.11 | NA |
| East Midlands | NA | NA | NA |
| London | 149.28 | 39.91 | NA |
| North East | NA | NA | NA |
| North West | NA | 32.60 | NA |
| South East | NA | 69.61 | NA |
| South West | NA | 53.77 | NA |
| West Midlands | NA | 59.69 | NA |
| Yorkshire and The Humber | NA | 124.65 | NA |
NB: negative growth rates are rates of decline. Values are daily changes.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 0.00 | 0.00 | 0.01 |
| East of England | 0.01 | 0.00 | 0.03 |
| East Midlands | -0.02 | -0.03 | -0.01 |
| London | 0.02 | 0.00 | 0.03 |
| North East | -0.02 | -0.03 | 0.00 |
| North West | 0.00 | -0.02 | 0.02 |
| South East | 0.00 | -0.01 | 0.02 |
| South West | 0.00 | -0.01 | 0.02 |
| West Midlands | 0.00 | -0.01 | 0.01 |
| Yorkshire and The Humber | -0.01 | -0.02 | 0.00 |
Halving times in days, if a region shows growth than value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | NA | 382.47 | NA |
| East of England | NA | NA | NA |
| East Midlands | 37.21 | 24.05 | 126.40 |
| London | NA | NA | NA |
| North East | 39.70 | 23.09 | 236.18 |
| North West | 8895.64 | 41.18 | NA |
| South East | NA | 96.61 | NA |
| South West | NA | 70.09 | NA |
| West Midlands | 3275.01 | 53.69 | NA |
| Yorkshire and The Humber | 64.60 | 28.73 | NA |
Doubling times in days, if a region shows decline then the value will be NA.
| Region | Median | 95% CrI (lower) | 95% CrI (upper) |
|---|---|---|---|
| England | 234.68 | 83.38 | NA |
| East of England | 53.56 | 26.14 | 1664.71 |
| East Midlands | NA | NA | NA |
| London | 45.75 | 24.68 | 212.29 |
| North East | NA | NA | NA |
| North West | NA | 36.05 | NA |
| South East | 147.51 | 37.74 | NA |
| South West | 347.54 | 40.85 | NA |
| West Midlands | NA | 51.20 | NA |
| Yorkshire and The Humber | NA | 197.24 | NA |
## The execution of the prevalence code block will proceed if
## prev.dat exists and this is TRUE
## it is not and external report and this is FALSEThe shaded areas show periods of national lockdown, the green lines the dates (once confirmed) of the steps in the roadmap in the UK Governement’s COVID-19 Response – Spring 2021, and the red line shows the date these results were produced (17 Dec).